Waveforms from Sunday’s earthquake

Later this month, the Washington Emergency Management Division will hold its annual ShakeOut Day of earthquake drills at workplaces, schools, and homes across the state. Sunday night, the earth provided a small preview.

Observers at the Pacific Northwest Seismic Network said the region was struck by a 4.3 magnitude earthquake at 7:21 PM with an epicenter 35 miles below Marrowstone Island — about 55 miles from the city.

There were no reports of damage but plenty of reports of people who felt the ripples across the area, Seattle, and on Capitol Hill.

Sunday’s earthquake was the first in the state with a magnitude of 4 or higher since 2019.

Also a reminder that Oct. 19 is the Great Washington ShakeOut for you to practice your earthquake drill skills! https://t.co/1q87g4o45E https://t.co/IuY9lMkyCv

— WA Emergency Management (@waEMD) October 9, 2023

The ShakeAlert early warning system that finally came online in the region last year detected the quake but the event was too small to issue an alert, according to the Pacific Northwest Seismic Network.

October 19th will bring the state’s annual Great Washington Shakeout to help communities organize earthquake drills.

While Seattle is still largely unprepared for a huge quake and the city has stalled on requiring retrofits of its highest risk brick buildings including 49 around Capitol Hill and the Central District. A new plan, meanwhile, is testing a solar microgrid system at Capitol Hill’s Miller Community Center that is designed to give the facility greater resiliency in the event of natural disasters and the Hill’s Lowell Elementary School received a $260,000 seismic retrofit.

The city’s more standard housing stock, meanwhile, will also need to withstand a major earthquake. Since 2001’s large Nisqually quake, many of the city’s buildings have been reinforced like the Piston and Ring preservation-friendly overhaul on 12th. Here’s a look at how Capitol Hill’s greatest old buildings stand up, with elegance, to earthquakes. But a 2012 survey effort by the city showed Capitol Hill is home to one of the largest clusters of unreinforced masonry buildings in the city.

Researchers have also tested one of the most unique new apartment buildings rising on the Hill for its ability to withstand an earthquake. The mass-timber Heartwood Apartments went through a research process to test the strength of cross-laminated timber.

Seattle has two primary faults: The Seattle Fault that runs east-west through the middle of the city, capable of earthquakes up to 7.4 magnitude, and the Cascadia Subduction Zone along the coast, capable of a magnitude 9 earthquake.

In recent years, Seattle officials have shifted advice for city dwellers for being prepared for the next big quake from having enough supplies for three days to “a more realistic” seven to ten days. Kits should include one gallon of water per person per day, food, a light source, and a first aid kit.

In the meantime, a collection of volunteers will help the area’s neighborhoods in the event of a catastrophe. CHS reported here on a drill this summer run by the North Capitol Hill Emergency Hub, part of volunteer-run efforts across the city trying to form a patchwork but still strong network of community plans and resources for how to keep neighborhoods safe and working when natural disasters and emergencies strike and people need to depend on each other.

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